A horror movie testing two approaches to running an insane asylum - absolute freedom versus control and punishment - within the context of a world that combines the worst of both. Jean Berlot, a young man subject to a nightmare of being forced into a straitjacket by two orderlies, is befriended by a marquis. At the marquis's estate, Jean witnesses a black Mass, buries someone alive, and is invited to try preventive therapy. He's willing to enter a sanatorium because he believes he can rescue a young woman from there who has told him that the real director and staff of the clinic are locked in the basement. Jean conspires with her to set them free: the horrors have only begun.